It turned out that the virtuozzo software was having a small bug itself with iptable modules which forced the main hardware node reboot. We have had to update this manually, and it's working fine now.
We have also discussed this with Parallels and they assured us that this will not happen again.
It is possible that your
VPS Hosting was not set to autostart with node when node got rebooted. We have set autostart for all
VPS Hosting's on the main hardware node.